Power diode and method of manufacturing a power diode

ABSTRACT

A method of processing a power diode includes: creating an anode region and a drift region in a semiconductor body; and forming, by a single ion implantation processing step, each of an anode contact zone and an anode damage zone in the anode region. Power diodes manufactured by the method are also described.

RELATED APPLICATIONS

The instant application is a divisional of and claims priority to U.S.application Ser. No. 16/104,799 filed on Aug. 17, 2018 and incorporatedby reference herein in its entirety.

TECHNICAL FIELD

This specification refers to embodiments of a power diode and toembodiments of a method of processing a power diode. In particular, thisspecification is directed to embodiments of a power diode with aspecific semiconductor anode structure and to corresponding processingmethods.

BACKGROUND

Many functions of modern devices in automotive, consumer and industrialapplications, such as converting electrical energy and driving anelectric motor or an electric machine, rely on power semiconductordevices. For example, Insulated Gate Bipolar Transistors (IGBTs), MetalOxide Semiconductor Field Effect Transistors (MOSFETs) and power diodes,to name a few, have been used for various applications including, butnot limited to switches in power supplies and power converters.

A power diode usually comprises a semiconductor body configured toconduct a load current along a load current path between two loadterminals of the diode, if a voltage in a forward direction is appliedbetween said terminals. If a voltage in a backward direction is applied,the power diode usually assumes a blocking state and flow of a loadcurrent is inhibited.

The load terminals of a power diode are usually referred to as anodeterminal and cathode terminal, and a transition from a conducting stateto a blocking state of the power diode may follow a reverse recoverybehavior of the power diode.

If employed in a certain application, it may be desirable that a toohigh charge carrier concentration in proximity to the anode terminal isavoided such that high current peaks during the reverse recovery may beavoided.

SUMMARY

According to an embodiment, a method of processing a power diodecomprises: providing a semiconductor body; creating an anode region anda drift region in the semiconductor body; forming, by a single ionimplantation processing step, each of an anode contact zone and an anodedamage zone in the anode region.

According to another embodiment, a power diode comprises: asemiconductor body with an anode region and a drift region, thesemiconductor body being coupled to an anode metallization of the powerdiode and to a cathode metallization of the power diode; an anodecontact zone and an anode damage zone, both implemented in the anoderegion, the anode contact zone being arranged in contact with the anodemetallization, and the anode damage zone being arranged in contact withand below the anode contact zone; wherein the anode damage zone extendsinto the anode region along a vertical direction no further than down toan extension level of 75 nm, measured from a transition between theanode metallization and the anode contact zone.

According to a further embodiment, a power diode comprises: asemiconductor body with an anode region and a drift region, thesemiconductor body being coupled to an anode metallization of the powerdiode and to a cathode metallization of the power diode; an anodecontact zone and an anode damage zone, both implemented in the anoderegion, the anode contact zone being arranged in contact with the anodemetallization, and the anode damage zone being arranged in contact withand below the anode contact zone; wherein fluorine is included withineach of the anode contact zone and the anode damage zone at a fluorineconcentration of at least 10¹⁶ atoms*cm⁻³.

Those skilled in the art will recognize additional features andadvantages upon reading the following detailed description, and uponviewing the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The parts in the figures are not necessarily to scale, instead emphasisbeing placed upon illustrating principles of the invention. Moreover, inthe figures, like reference numerals designate corresponding parts. Inthe drawings:

FIG. 1 schematically and exemplarily illustrates an aspect of a methodof processing a power diode in accordance with one or more embodiments;

FIG. 2 schematically and exemplarily illustrates a section of a verticalcross-section of a power diode in accordance with one or moreembodiments;

FIG. 3 schematically and exemplarily illustrates a course of an electricfield and courses of charge carrier concentrations present in asemiconductor body of a power diode in accordance with one or moreembodiments; and

FIG. 4 schematically and exemplarily illustrates a section of thediagram of FIG. 3 in an enlarged view.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings which form a part hereof and in which are shown byway of illustration specific embodiments in which the invention may bepracticed.

In this regard, directional terminology, such as “top”, “bottom”,“below”, “front”, “behind”, “back”, “leading”, “trailing”, “above” etc.,may be used with reference to the orientation of the figures beingdescribed. Because parts of embodiments can be positioned in a number ofdifferent orientations, the directional terminology is used for purposesof illustration and is in no way limiting. It is to be understood thatother embodiments may be utilized and structural or logical changes maybe made without departing from the scope of the present invention. Thefollowing detailed description, therefore, is not to be taken in alimiting sense, and the scope of the present invention is defined by theappended claims.

Reference will now be made in detail to various embodiments, one or moreexamples of which are illustrated in the figures. Each example isprovided by way of explanation, and is not meant as a limitation of theinvention. For example, features illustrated or described as part of oneembodiment can be used on or in conjunction with other embodiments toyield yet a further embodiment. It is intended that the presentinvention includes such modifications and variations. The examples aredescribed using specific language which should not be construed aslimiting the scope of the appended claims. The drawings are not scaledand are for illustrative purposes only. For clarity, the same elementsor manufacturing steps have been designated by the same references inthe different drawings if not stated otherwise.

The term “horizontal” as used in this specification intends to describean orientation substantially parallel to a horizontal surface of asemiconductor substrate or of a semiconductor structure. This can be forinstance the surface of a semiconductor wafer or a die or a chip. Forexample, both the first lateral direction X and the second lateraldirection Y mentioned below can be horizontal directions, wherein thefirst lateral direction X and the second lateral direction Y may beperpendicular to each other.

The term “vertical” as used in this specification intends to describe anorientation which is substantially arranged perpendicular to thehorizontal surface, i.e., parallel to the normal direction of thesurface of the semiconductor wafer/chip/die. For example, the extensiondirection Z mentioned below may be an extension direction that isperpendicular to both the first lateral direction X and the secondlateral direction Y. The extension direction Z is also referred to as“vertical direction Z” herein.

In this specification, n-doped is referred to as “first conductivitytype” while p-doped is referred to as “second conductivity type”.Alternatively, opposite doping relations can be employed so that thefirst conductivity type can be p-doped and the second conductivity typecan be n-doped.

In the context of the present specification, the terms “in ohmiccontact”, “in electric contact”, “in ohmic connection”, and“electrically connected” intend to describe that there is a low ohmicelectric connection or low ohmic current path between two regions,sections, zones, portions or parts of a semiconductor device or betweendifferent terminals of one or more devices or between a terminal or ametallization or an electrode and a portion or part of a semiconductordevice. Further, in the context of the present specification, the term“in contact” intends to describe that there is a direct physicalconnection between two elements of the respective semiconductor device;e.g., a transition between two elements being in contact with each othermay not include a further intermediate element or the like.

In addition, in the context of the present specification, the term“electric insulation” is used, if not stated otherwise, in the contextof its general valid understanding and thus intends to describe that twoor more components are positioned separately from each other and thatthere is no ohmic connection connecting those components. However,components being electrically insulated from each other may neverthelessbe coupled to each other, for example mechanically coupled and/orcapacitively coupled and/or inductively coupled. To give an example, twoelectrodes of a capacitor may be electrically insulated from each otherand, at the same time, mechanically and capacitively coupled to eachother, e.g., by means of an insulation, e.g., a dielectric.

Specific embodiments described in this specification pertain to, withoutbeing limited thereto a power semiconductor device that may be usedwithin a power converter or a power supply. Thus, in an embodiment, suchdevice can be configured to carry a load current that is to be fed to aload and/or, respectively, that is provided by a power source. Forexample, the power semiconductor device may comprise one or more activepower semiconductor cells, such as a monolithically integrated diodecell, and/or a monolithically integrated transistor cell, and/or amonolithically integrated IGBT cell, and/or a monolithically integratedRC-IGBT cell, and/or a monolithically integrated MOS Gated Diode (MGD)cell, and/or a monolithically integrated MOSFET cell and/or derivativesthereof. Such diode cells and/or such transistor cells may be integratedin a power semiconductor module. A plurality of such cells mayconstitute a cell field that is arranged with an active region of thepower semiconductor device.

The present specification further relates to a power semiconductordevice in the form of a power diode.

The term “power diode” as used in this specification intends to describea semiconductor device on a single chip with high voltage blockingand/or high current-carrying capabilities. In other words, such powerdiode is intended for high current, typically in the Ampere range, e.g.,up to several ten or hundred Ampere, and/or high voltages, typicallyabove 15 V, more typically 100 V and above, e.g., up to at least 400 V.

For example, the power diode described below may be a semiconductordevice configured to be employed as a power component in a low-, medium-and/or high voltage application. For example, the term “power diode” asused in this specification is not directed to logic semiconductordevices that are used for, e.g., storing data, computing data and/orother types of semiconductor based data processing.

FIG. 1 schematically and exemplarily illustrates an aspect of a methodof processing a power diode 1. The method may comprise providing asemiconductor body 10 and creating each of an anode region 102 and adrift region 100 in the semiconductor body 10. Creating the drift region100 may occur separately from creating the anode region 102.

The drift region 100 may comprise dopants of the first conductivitytype. For example, the drift region 100 is n-doped. The drift region 100may exhibit a dopant concentration of dopants of the first conductivitytype within the range of 10¹² cm⁻³ to 5*10¹⁴ cm⁻³. For example, thedopant concentration of the drift region 100 and its total extensionalong the vertical direction Z are chosen in dependence on the voltagerating for which the power diode shall be designed.

The anode region 102 may comprise dopants of the second conductivitytype. For example, the anode region 102 is p-doped. Creating the anoderegion 102 may comprise at least one of an implantation processing stepand a diffusion processing step. For example, by means of creating theanode region 102, a base dopant concentration can be achieved in theanode region 102, wherein the base dopant concentration may have aprofile with a doping concentration that decreases in the verticaldirection Z, e.g., a diffusion profile. Alternatively, the anode region102 may have a base dopant concentration which is substantiallyhomogenously distributed within the anode region 102.

Embodiments described herein relate to modifying the anode region 102 interms of locally adjusting the dopant concentration and/or a defectconcentration within the anode region 102 that may initially exhibitsaid base dopant concentration.

For example, the method of processing the power diode 1 may includeforming, by a single ion implantation processing step, each of an anodecontact zone 1021 and an anode damage zone 1022 in the anode region 102.

Within the scope of the present specification, the term “single ionimplantation processing step” may designate an uninterruptedimplantation processing step that is carried out with non-variation ofthe implantation energy, with non-variation of the implantation dose andwith non-variation of the implantation ions. For example, in order tocarry out said single ion implantation processing step, an ionimplantation device is controlled by means of setting controlparameters, e.g., a fixed implantation energy range, a fixedimplantation dose range, a fixed implantation duration, and a fixedambient temperature range. Said single ion implantation processing stepin this context may also be understood as the sequence of two or moreuninterrupted implantation shots that are carried out each withnon-variation of the implantation energy, with non-variation of theimplantation dose and with non-variation of the implantation ions.

For example, the ion implantation device used for carrying out thesingle ion implantation processing step is abeamline-implantation-device. For example, a beamline implantation toolis provided that separates the isotopes or species (e.g. ionized atomsor molecules) to be implanted. For example, the isotopes or species arefocused in a beam and post-accelerated to the desired energy before theyhit the semiconductor body. The beamline-implantation-device may implantmonoenergetic species of the same relation mass to charge by eitherscanning the semiconductor wafer by deflection of the beam or moving thesemiconductor wafer under the fixed beam.

For example, the single ion implantation processing step comprisesimplanting heavy ions. The heavy ions may comprise ions with a massexceeding that of the ₆ ¹²carbon-nucleus or the ₁₄ ²⁸silicium-nucleus.

In an embodiment, the single ion implantation processing step comprisesimplanting ionized boron difluoride (BF₂) molecules. The single ionimplantation processing step can be realized by a pure BF₂ ionimplantation.

For example, the single ion implantation processing step is carried withan implantation energy of less than 30 keV or less than 20 keV. Forexample, the single ion implantation processing step is carried suchthat the a mean distance of the implanted ions, measured from a surface10-1 of the provided semiconductor body 10 that has been penetrated bythe implanted ions, amounts to less than 100 nm. This mean distance canbe even shorter, e.g., shorter than 80 nm, shorter than 70 nm or evenshorter than 50 nm. A possible measure to adjust the mean distance isnot only the implantation energy applied during the single ionimplantation processing step, but also a thickness of thin oxide layer(not illustrated) at the surface 10-1 that may come into being duringpreparation of the single ion implantation processing step.

Further, the single ion implantation processing step can be carried outwith an implantation dose of at least 2*10¹³ cm⁻². The implantation dosecan be greater than 2*10¹³ cm⁻², e.g., greater than 3*10¹³ cm⁻², or evengreater than 6*10¹³ cm⁻².

In an embodiment of the method, the single ion implantation processingstep is followed by a temperature annealing processing step that iscarried out at a temperature smaller than 450° C., wherein defectscaused by the implanted ions are only partially annealed. Thetemperature can be kept smaller than 450° C., e.g., smaller than 420° C.or smaller than 400° C. The duration of the temperature annealingprocessing step may dependent on several factors and may be within therange of some minutes to some hours.

For example, due to such low-temperature annealing processing step, itcan be ensured that predominantly defects in proximity to the surface10-1 are partially annealed, thereby forming the anode contact zone 1021with a comparatively lower defect concentration and a comparativelyhigher dopant concentration. For example, the anode contact zone 1021may exhibit a high dopant concentration of dopants of the secondconductivity type and/or alternatively a high interstitial density,e.g., within the range of 10¹⁸ cm⁻³ to 10²⁰ cm⁻³.

For example, due to such low-temperature temperature annealingprocessing step, it can further be ensured that predominantly defectsspatially displaced from the surface 10-1 are not annealed, therebyforming the anode damage zone 1022 with a comparatively high defectconcentration and a comparatively low dopant concentration. For example,the anode damage zone 1022 may exhibit a high defect concentration,e.g., within the range of 10¹⁸ cm⁻³ to 10²⁰ cm⁻³.

In an embodiment, the created anode damage zone 1022 can be configuredto reduce at least one of a lifetime and a mobility of charge carrierspresent within the anode damage zone 1022. For example, the damage zone1022 can be configured to reduce the emitter efficiency of the anoderegion 102.

Now it is additionally referred to FIG. 2 , which schematically andexemplarily illustrates a section of a vertical cross-section of a powerdiode 1 in accordance with one or more embodiments. The power diode 1may have been produced in accordance with the method described above.Thus, what has been stated with respect to FIG. 1 may equally apply tothe embodiment of FIG. 2 . Analogously, what will now be stated withrespect to FIG. 2 may equally apply to the embodiment of FIG. 1 .

In an embodiment of the method, before carrying out the single ionimplantation processing step, a first implantation processing step iscarried out for forming an anode field stop zone 1024 within the anoderegion 102, the anode field stop zone 1024 being arranged deeper withinthe anode region 102 than each of the anode contact zone 1021 and theanode damage zone 1022. The anode field stop zone 1024 can be spatiallyseparated from the anode damage zone 1022, e.g., by means of an anodebody zone 1023, as will be explained in more detail below.

For example, at first the anode region 102 is created by means ofproviding said base dopant concentration, e.g., by at least one of animplantation processing step and a diffusion processing step. Forexample, the base dopant concentration of the anode region 102 can beachieved with boron as the dopant material. In the illustratedembodiments, the region referred to with reference numeral 1023 maydesignate an anode body zone that may essentially exhibit said basedopant concentration.

Thereafter, the anode field stop zone 1024 may be formed by carrying outthe first implantation processing step that is different from the singleion implantation processing step. The anode field stop zone 1024 may bearranged in a lower part of the anode region 102 or may even terminatethe anode region 1024. Further, implantation particles introduced in theanode region 102 by means of the first implantation processing step canbe subjected to a temperature annealing processing step so as to annealdefects caused by said implantation particles, e.g., so as to completelyanneal the defects caused by said implantation particles. This may yielda comparatively high dopant concentration within the anode field stopzone 1024, e.g., a dopant concentration greater than the dopantconcentration of the anode body zone(s) 1023.

The anode field stop zone 1024 may exhibit a dopant concentration ofdopants of the second conductivity type within the range of 5e16 cm⁻³ to7e17 cm⁻³. For example, this dopant concentration is achieved by meansof implanted boron ions that are afterwards subjected to the temperatureannealing processing step.

Then, i.e., after the anode field stop zone 1024 has been created, e.g.,subsequent to the first implantation processing step and the temperatureannealing processing step following thereafter, the single ionimplantation processing step may be carried out for forming the anodecontact zone 1021 and the anode damage zone 1022.

Thus, it shall be understood, that in accordance with an embodiment,prior to the single ion implantation processing step, the dopantconcentration of the anode region 102 can be adjusted, e.g., by means ofimplanting boron. The anode body zone(s) 1023 of the anode region 102that do not form a part of one of the anode contact zone 1021, the anodedamage zone 1022 and the anode field stop zone 1024 can exhibit a dopantconcentration of dopants of the second conductivity type within therange of 1*10¹⁶ cm⁻³ to 2*10¹⁷ cm⁻³.

In an embodiment, the anode field stop zone 1024 is spatially displacedfrom the anode damage zone 1022 by at least 250 nm along the verticaldirection Z. This distance can be even greater than 250 nm, e.g.,greater than 400 nm or greater than 600 nm. It shall be understood thatthis distance between the anode field stop zone 1024 and the anodedamage zone 1022 may refer to the distance between a peak of the defectconcentration of the anode damage zone 1022 and a peak of the dopantconcentration of the anode field stop zone 1024. The anode field stopzone 1024 and the anode damage zone 1022 may be separated from eachother by means of the anode body zone 1023.

Finally, after the single ion implantation processing step, an anodemetallization 11 may be provided on top of the anode region 102. Forexample, the anode contact zone 1021 of the anode region 102 may bearranged in contact with the anode metallization 11.

Now referring more specifically to FIG. 2 , the power diode 1 comprisesa semiconductor body 10 with an anode region 102 and a drift region 100,the semiconductor body 10 being coupled to an anode metallization 11 ofthe power diode 1 and to a cathode metallization 12 of the power diode1. The anode metallization 11 may form a part of an anode load terminalof the power diode 1, and the cathode metallization 12 may form a partof a cathode load terminal of the power diode 1. Regarding the anoderegion 102 and the drift region 100 of the semiconductor body 10, theexplanations already given above may apply.

Accordingly, an anode contact zone 1021 and an anode damage zone 1022may both be implemented in the anode region 102. The anode contact zone1021 can be arranged in contact with the anode metallization 11 and theanode damage zone 1022 can be arranged in contact with and below theanode contact zone 1021. The anode contact zone 1021 and the anodedamage zone 1022 may have been produced in accordance with the methoddescribed above, e.g., by means of the single ion implantationprocessing step.

For example, the semiconductor body 10 further comprises a cathodecontact region 108, wherein the drift region 100 can be coupled to thecathode metallization 12 by means of the cathode contact region 108. Forexample, the cathode contact region 108 is arranged in contact with thecathode metallization 12 and may exhibit a dopant concentration ofdopants of the first conductivity type within the range of 5*10¹⁹ cm⁻³to 5*10²⁰ cm⁻³.

The power diode 1-1 may comprise, e.g., a pin or a pn⁻n structured thatis formed by the anode region 102 (p), the drift region 100 (i or n⁻)and the cathode contact region 108 (n).

In an embodiment, the anode damage zone 1022 extends into the anoderegion 102 along the vertical direction Z no further than down to anextension level of 75 nm, measured from the surface 10-1 of thesemiconductor body 10-1, which may be at the same level as a transitionbetween the anode metallization 11 and the anode contact zone 1021. Inaddition or in alternative thereto, fluorine can be included within eachof the anode contact zone 1021 and the anode damage zone 1022 at afluorine concentration of at least 10¹⁶ atoms*cm⁻³.

The extension level can be smaller than 75 nm, e.g., smaller than 50 nmor even smaller than 20 nm. In other words, in an embodiment, the alower termination 10221 of the anode damage zone 1022 is spaced apartfrom the surface 10-1 of the semiconductor body 10, e.g., from thetransition between the anode metallization 11 and the anode region 102by no more than 75 nm, no more than 50 nm or no more than 20 nm. Inother words, the anode damage zone 1022 may be arranged below the anodecontact zone 1021, yet be positioned very close to the anodemetallization 11 and sufficiently far away from the pn-junction formedbetween the anode region 102 and the drift region 100.

Said fluorine concentration can also be greater than 10¹⁶ atoms*cm⁻³,e.g., greater than 5*10¹⁷ atoms*cm⁻³ or even greater than 10¹⁹atoms*cm⁻³.

For example, the anode region 102 extends into the semiconductor body 10along the vertical direction Z for at least 2 μm, for at least 4 μm orfor at least 6 μm.

Further, in an embodiment, a distance between a peak of the electricfield during a blocking state of the power diode 1 and the lowertermination 10221 of the anode damage zone 1022 may amount to at least250 nm, to at least 400 nm or to at least 600 nm. Such distance betweenthe peak E_(MAX) of the electric field E during a blocking state of thepower diode 1 and the lower termination 10221 is exemplarily illustratedin FIGS. 3 and 4 and referenced as ΔZ. For example, the power diode 1can be configured, e.g., by means of said distance ΔZ, such that a spacecharge region, e.g., during a blocking state of the power diode 1, doesnot extend into the damage zone 1022.

Now referring to FIG. 3 in more detail, exemplary extensions and dopantconcentration N_(A) (p-type dopants), N_(D) (n-type dopants) and defect(D) concentrations shall be explained. It shall be understood that theseexemplarily values may apply to all embodiments described aboveregarding both the method and the power diode 1. FIG. 4 illustrates asection of the courses of dopant concentrations N_(A) and N_(D) and thedefect concentration D as well as the course of the electric field E ofFIG. 3 in an enlarged view.

The anode contact zone 1021, which may be arranged in contact with theanode metallization 11, and which may exhibit an upper termination thatmay form a part of the surface 10-1, may be p-doped at a highconcentration of approximately 10¹⁹ cm⁻³. Further, a fluorineconcentration of at least 10¹⁶ atoms*cm⁻³ may be present in the anodecontact zone 1021. The anode contact zone 1021 may have a totalextension in the vertical direction Z of approximately 50 nm up to 200nm.

The anode damage zone 1022, which may be arranged below and in contactwith the anode contact zone 1021, may exhibit a high defectconcentration of approximately 10¹⁹ cm⁻³. Further, a fluorineconcentration of at least 10¹⁶ atoms*cm⁻³ may be present in the anodedamage zone 1022. The anode damage zone 1022 may have a total extensionin the vertical direction Z of approximately 100 nm up to 400 nm.

As has been explained above, the anode contact zone 1021 and the anodedamage zone 1022 may be formed by a single ion implantation processingstep and a subsequent temperature annealing processing step during whichthe defects caused by the ion implantation are only partially annealed.

The anode body zone(s) 1023 arranged below the anode damage zone 1022may be p-doped at a base concentration of approximately 10¹⁷ cm⁻³. Theanode body zone(s) 1023 may have a total extension in the verticaldirection Z of approximately 200 nm up to 700 nm. As has been explainedabove, the anode region 102 may include the anode field stop zone 1024,either as a zone that terminates the anode region 102 in the verticaldirection Z or as a zone arranged between two anode body zones 1023 asillustrated in FIG. 3 . The anode field stop zone 1024 may be p-doped ata higher concentration than the anode body zone(s) 1023, e.g., with aconcentration of approximately 10¹⁸ cm⁻³. The anode field stop zone 1024may have a total extension in the vertical direction Z of approximately200 nm up to 600 nm.

The drift region 100 may be n-doped at a low dopant or an intrinsicconcentration, e.g., with a concentration of up to 5*10¹⁴ cm⁻³. Forexample, the dopant concentration of the drift region 100 and its totalextension along the vertical direction Z are chosen in dependence on thevoltage rating for which the power diode 1 shall be designed.

The drift region 100 can be coupled to the cathode metallization 12 bymeans of the cathode contact region 108. For example, the cathodecontact region 108 is arranged in contact with the cathode metallization12 and may be n-doped at a dopant concentration of approximately 1*10²⁰cm⁻³. For example, the cathode contact region 108 has a total extensionalong the vertical direction Z of up to 0.3 μm.

Embodiments described above include the recognition that a power diodewith an anode that only weakly emits holes can be achieved with an anodethat has a highly doped contact zone and a damage zone. However, undercircumstances, e.g., a high operating temperatures, such damage zone mayalso act as a charge carrier generation zone. For avoiding such effect,it can be ensured that the space charge region does not extend into thedamage zone. In accordance with one or more embodiment described above,it is proposed to provide for a very narrow anode damage zone that issufficiently far spatially displaced from the space charge region,without having the need of providing a deep reaching anode region. Forexample, such damage zone can be formed by means of a single BF₂implantation that is followed by a temperature annealing processing stepduring which the BF₂ defects are only partially annealed, so as tosimultaneously produce the anode damage zone and the anode contact zoneon top thereof that is to interface with the anode metallization. Inaccordance with an embodiment, for forming the anode damage zone and thecontact zone, not boron but BF₂ is implanted.

In the above, embodiments pertaining to power diodes and correspondingprocessing methods were explained. For example, these power diodes arebased on silicon (Si). Accordingly, a monocrystalline semiconductorregion or layer, e.g., the semiconductor body 10 and its regions/zones,e.g., regions 100, 102, 108 etc. can be a monocrystalline Si-region orSi-layer. In other embodiments, polycrystalline or amorphous silicon maybe employed.

It should, however, be understood that the semiconductor body 10 and itsregions/zones can be made of any semiconductor material suitable formanufacturing a power diode. Examples of such materials include, withoutbeing limited thereto, elementary semiconductor materials such assilicon (Si) or germanium (Ge), group IV compound semiconductormaterials such as silicon carbide (SiC) or silicon germanium (SiGe),binary, ternary or quaternary III-V semiconductor materials such asgallium nitride (GaN), gallium arsenide (GaAs), gallium phosphide (GaP),indium phosphide (InP), indium gallium phosphide (InGaPa), aluminumgallium nitride (AlGaN), aluminum indium nitride (AlInN), indium galliumnitride (InGaN), aluminum gallium indium nitride (AlGaInN) or indiumgallium arsenide phosphide (InGaAsP), and binary or ternary II-VIsemiconductor materials such as cadmium telluride (CdTe) and mercurycadmium telluride (HgCdTe) to name few. The aforementioned semiconductormaterials are also referred to as “homojunction semiconductormaterials”. When combining two different semiconductor materials aheterojunction semiconductor material is formed. Examples ofheterojunction semiconductor materials include, without being limitedthereto, aluminum gallium nitride (AlGaN)-aluminum gallium indiumnitride (AlGaInN), indium gallium nitride (InGaN)-aluminum galliumindium nitride (AlGaInN), indium gallium nitride (InGaN)-gallium nitride(GaN), aluminum gallium nitride (AlGaN)-gallium nitride (GaN), indiumgallium nitride (InGaN)-aluminum gallium nitride (AlGaN),silicon-silicon carbide (SixC1-x) and silicon-SiGe heterojunctionsemiconductor materials. For power semiconductor devices applicationscurrently mainly Si, SiC, GaAs and GaN materials are used.

Spatially relative terms such as “under”, “below”, “lower”, “over”,“upper” and the like, are used for ease of description to explain thepositioning of one element relative to a second element. These terms areintended to encompass different orientations of the respective device inaddition to different orientations than those depicted in the figures.Further, terms such as “first”, “second”, and the like, are also used todescribe various elements, regions, sections, etc. and are also notintended to be limiting. Like terms refer to like elements throughoutthe description.

As used herein, the terms “having”, “containing”, “including”,“comprising”, “exhibiting” and the like are open ended terms thatindicate the presence of stated elements or features, but do notpreclude additional elements or features.

With the above range of variations and applications in mind, it shouldbe understood that the present invention is not limited by the foregoingdescription, nor is it limited by the accompanying drawings. Instead,the present invention is limited only by the following claims and theirlegal equivalents.

What is claimed is:
 1. A power diode, comprising: a semiconductor bodyhaving an anode region and a drift region, the semiconductor body beingcoupled to an anode metallization of the power diode and to a cathodemetallization of the power diode; and an anode contact zone and an anodedamage zone, both implemented in the anode region, the anode contactzone being arranged in contact with the anode metallization, and theanode damage zone being arranged in contact with and below the anodecontact zone, wherein the anode damage zone extends into the anoderegion along a vertical direction no further than down to an extensionlevel of 75 nm, measured from a surface of the semiconductor body. 2.The power diode of claim 1, wherein the anode region extends into thesemiconductor body along the vertical direction for at least 2 μm. 3.The power diode of claim 1, wherein a distance between a peak electricfield during a blocking state of the power diode and a lower terminationof the anode damage zone is at least 250 nm.
 4. The power diode of claim1, wherein a space charge region does not extend into the anode damagezone.
 5. The power diode of claim 1, wherein the semiconductor bodyfurther comprises a cathode contact region, wherein the drift region iscoupled to the cathode metallization by the cathode contact region. 6.The power diode of claim 1, wherein the anode region further comprisesan anode body zone disposed below the anode damage zone.
 7. The powerdiode of claim 6, wherein the anode body zone has a total extension inthe vertical direction of between 200 nm and 700 nm.
 8. The power diodeof claim 7, wherein the anode region further comprises an anode fieldstop zone, wherein the anode field stop zone forms a termination of theanode region, or wherein the anode field stop zone is disposed betweentwo of the anode body zones.
 9. The power diode of claim 8, wherein theanode field stop zone is spaced apart from the anode damage zone by atleast 250 nm in the vertical direction.
 10. The power diode of claim 9,wherein a distance between a peak electric field during a blocking stateof the power diode and a lower termination of the anode damage zone isat least 250 nm.